The present invention relates to universal joint yokes and, in particular, relates to yokes formed from a sheet metal blank or a tube length, such as by cutting and cold rolling.
Universal joints are known to comprise two yokes each having a tubular hub for mounting on a transmission shaft or the like and a cross-piece the four trunnions of which each have a thin-walled bearing race mounted in a bore in a respective yoke arm. The rotational axis of the tubular hub and the common axis of the yoke arm bores defining a plane of symmetry in the yoke.
In order to ensure optimum support for each race in its bore on both sides of the plane of symmetry, a technique was proposed (in U.S. Pat. No. 3,501,928) to give a substantially circular-based cylindrical form to the yoke so that, in a plane perpendicular to the rotational axis and passing through the common axis of the bores, support was given by the two circular arcs centred on the rotational axis of the cross-piece and defining the cylindrical form.
Very satisfactory support for the bearing races and consequent adequate transmission of forces can be obtained by use of this technique in yokes formed from sheet metal blanks or tube lengths of sufficient thickness.
This technique has come into widespread use because of its numerous advantages but it has not been applied to lightened universal joints because of the insufficient race support that could be provided by a thin metal sheet or tube.
One known solution is to draw a peripheral neck from the sheet metal blank about the bore but this solution, apart from its complexity, makes the fitting of a cross-piece into the yoke by simple tilting impossible.